Round Head Screws Manufacturer in India | Round Head Machine Screws

Overview

Round Head Machine Screws & Round Head Wood Screws: Manufacturer & Supplier

A round head screw has a full dome over a flat bearing face. It sits on the surface, looks finished, and is the traditional head for electrical gear, instruments, hardware and woodwork.

Exotic Alloy manufactures round head screws in Mumbai, India, for electrical, instrument, hardware and equipment makers. We stock across India and supply Mexico, North and South America, the Gulf and Europe. Heads are cold formed with the slot or cross recess in one blow, and threads are rolled.

Machine screw or wood screw

Inch round head machine screws follow ASME B18.6.3 and take a nut or a tapped hole. Metric round head wood screws follow DIN 96 (slotted) and DIN 7996 (cross recessed) and cut their own thread in timber. Need a flatter head? Compare the pan, truss and button head options.

ASME B18.6.3 DIN 96 / DIN 7996 Slotted & Phillips UNC / UNF Stainless & brass

Round head screw at a glance

Head: Full dome, flat bearing face
Drive: Slotted or Phillips, PH 1 to PH 4
Length: Measured from under the head
Threads: UNC / UNF (machine); wood screw thread (DIN 96 / 7996)
Materials: 18-8, 316, brass, zinc-plated steel
Related: Pan head, truss head, wood screws

No. 10-24 × 3/4″ round head machine screw, drawn to scale from the ASME B18.6.3 maximum dimensions (inches). The side view is cut through the slot; the top views show the slotted head and the Phillips recess (recess shape simplified).

Specification

Round Head Screw Specification

The range we manufacture and supply.

StandardsASME B18.6.3 (inch machine screws); DIN 96 and DIN 7996 (metric wood screws); metric machine screws to drawing

Size rangeNo. 2 to 1/2″; wood screws 1.6–8 mm

Lengths1/8″ to 3″ and 8–80 mm; longer to order

ThreadUNC / UNF, fully threaded; wood screw thread with gimlet point

DriveSlotted; Phillips (type H); Pozidriv (type Z) for DIN 7996

Materials18-8 stainless (304 / 305), 316 stainless, brass, low-carbon steel

FinishPlain or passivated stainless; plain or nickel-plated brass; zinc or black-oxide steel

HeadFull dome; slotted, Phillips or combination drive to order

CertificationMill certificate; EN 10204 3.1; PMI for stainless

PackingBoxes of 100 to 1000, bulk cartons, kits to order

Head types

Round Head vs Pan, Binding & Truss Heads

Four domed machine screw heads for the same No. 6 thread: the round head is the tallest, the truss head the widest.

No. 6 heads at the same scale, diameters and heights from ASME B18.6.3 (pan head from manufacturers’ B18.6.3 data); outlines simplified.

Size	Round A / H	Truss A / H	Binding A / O
No. 2	.162 / .069	.194 / .053	.181 / .050
No. 3	.187 / .078	.226 / .061	.208 / .059
No. 4	.211 / .086	.257 / .069	.235 / .068
No. 5	.236 / .095	.289 / .078	.263 / .078
No. 6	.260 / .103	.321 / .086	.290 / .087
No. 8	.309 / .120	.384 / .102	.344 / .105
No. 10	.359 / .137	.448 / .118	.399 / .123
No. 12	.408 / .153	.511 / .134	.454 / .141
1/4″	.472 / .175	.573 / .150	.525 / .165

Maximum head diameter and height, inches, ASME B18.6.3. Binding: slotted undercut head, total height O.

Dimensions

Round Head Screw Dimensions

The twelve ASME B18.6.3 round head sizes at the same scale, top view with Phillips recess and side profile.

Size	Basic dia. in	A head dia. max / min	H head height max / min	J slot width max / min	T slot depth max / min	UNC / UNF TPI
No. 2	.086	.162 / .146	.069 / .059	.031 / .023	.048 / .037	56 / 64
No. 3	.099	.187 / .169	.078 / .067	.035 / .027	.053 / .040	48 / 56
No. 4	.112	.211 / .193	.086 / .075	.039 / .031	.058 / .044	40 / 48
No. 5	.125	.236 / .217	.095 / .083	.043 / .035	.063 / .047	40 / 44
No. 6	.138	.260 / .240	.103 / .091	.048 / .039	.068 / .051	32 / 40
No. 8	.164	.309 / .287	.120 / .107	.054 / .045	.077 / .058	32 / 36
No. 10	.190	.359 / .334	.137 / .123	.060 / .050	.087 / .065	24 / 32
No. 12	.216	.408 / .382	.153 / .139	.067 / .056	.096 / .073	24 / 28
1/4″	.250	.472 / .443	.175 / .160	.075 / .064	.109 / .082	20 / 28
5/16″	.3125	.590 / .557	.216 / .198	.084 / .072	.132 / .099	18 / 24
3/8″	.375	.708 / .670	.256 / .237	.094 / .081	.155 / .117	16 / 24
1/2″	.500	.813 / .766	.355 / .332	.106 / .091	.211 / .159	13 / 20

ASME B18.6.3 round heads for machine screws, slotted, inches.

Size	A head dia. max / min	H head height max / min	M recess dia. max / min	G recess depth max	N recess width min	Phillips driver
No. 2	.162 / .146	.069 / .059	.100 / .087	.053	.017	PH 1
No. 3	.187 / .169	.078 / .067	.109 / .096	.062	.018	PH 1
No. 4	.211 / .193	.086 / .075	.118 / .105	.072	.019	PH 1
No. 5	.236 / .217	.095 / .083	.154 / .141	.074	.027	PH 2
No. 6	.260 / .240	.103 / .091	.162 / .149	.084	.027	PH 2
No. 8	.309 / .287	.120 / .107	.178 / .165	.101	.030	PH 2
No. 10	.359 / .334	.137 / .123	.195 / .182	.119	.031	PH 2
No. 12	.408 / .382	.153 / .139	.249 / .236	.125	.032	PH 3
1/4″	.472 / .443	.175 / .160	.268 / .255	.147	.034	PH 3
5/16″	.590 / .557	.216 / .198	.308 / .295	.187	.040	PH 3
3/8″	.708 / .670	.256 / .237	.387 / .374	.228	.064	PH 4
1/2″	.813 / .766	.355 / .332	.416 / .403	.256	.068	PH 4

ASME B18.6.3 round heads with Phillips (type I) recess, inches. Head dimensions are the same as the slotted head.

Thread d	d_k head dia. nom	k head height nom	n slot width nom	t slot depth max / min
1.6	3.2	1.1	0.4	0.7 / 0.55
2	4	1.4	0.5	0.9 / 0.7
2.5	5	1.7	0.6	1.1 / 0.85
3	6	2.1	0.8	1.35 / 1.05
3.5	7	2.4	0.8	1.6 / 1.2
4	8	2.8	1	1.8 / 1.4
4.5	9	3.1	1	2 / 1.55
5	10	3.5	1.2	2.3 / 1.75
5.5	11	3.8	1.2	2.5 / 1.9
6	12	4.2	1.6	2.7 / 2.1
7	14	4.9	2	3.2 / 2.45
8	16	5.6	2	3.6 / 2.8

DIN 96:2016 slotted round head wood screws, mm. The head is twice the thread diameter across and about 0.7 times it high.

Thread d	d_k head dia. nom	k head height nom	Cross recess size	m recess dia. ≈ H / Z
2	4	1.4	0	–
2.5	5	1.7	1	2.3 / 2.4
3	6	2.1	1	2.7 / 2.9
3.5	7	2.35	2	3.7 / 3.9
4	8	2.8	2	4.1 / 4.1
4.5	9	3.1	2	4.4 / 4.3
5	10	3.5	2	4.8 / 4.7
5.5	11	3.8	3	6.2 / 6.2
6	12	4.2	3	6.6 / 6.7
7	14	4.9	3	7.3 / 7
8	16	5.6	4	8.8 / 8.5

DIN 7996:2016 cross recessed round head wood screws, mm. H = Phillips, Z = Pozidriv recess.

Drives

Slotted or Phillips Round Head?

A slotted round head is the traditional choice: it can be turned with any flat blade, cleans out easily and suits restoration, period hardware and low-volume assembly. A Phillips recess centres the driver, so it is faster on the assembly line and with power drivers.

Use the matching driver size: the cross recess of a round head is shallow, and a worn or undersized bit will cam out and mark the dome. On slotted heads, use a blade that fills the slot width and length.

Phillips driver	Round head sizes
PH 1	No. 2, No. 3, No. 4
PH 2	No. 5, No. 6, No. 8, No. 10
PH 3	No. 12, 1/4″, 5/16″
PH 4	3/8″, 1/2″

From the ASME B18.6.3 round head table.

Tap drills

Threads & Tap Drills for Round Head Machine Screws

Every size comes in a coarse (UNC) and a fine (UNF) thread. These drills give about 75 % thread engagement in a tapped hole.

Size	UNC	Tap drill UNC	UNF	Tap drill UNF	Phillips driver
No. 2	#2-56	#50 (0.0700″)	#2-64	#50 (0.0700″)	PH 1
No. 3	#3-48	#47 (0.0785″)	#3-56	#45 (0.0820″)	PH 1
No. 4	#4-40	#43 (0.0890″)	#4-48	#42 (0.0935″)	PH 1
No. 5	#5-40	#38 (0.1015″)	#5-44	#37 (0.1040″)	PH 2
No. 6	#6-32	#36 (0.1065″)	#6-40	#33 (0.1130″)	PH 2
No. 8	#8-32	#29 (0.1360″)	#8-36	#29 (0.1360″)	PH 2
No. 10	#10-24	#25 (0.1495″)	#10-32	#21 (0.1590″)	PH 2
No. 12	#12-24	#16 (0.1770″)	#12-28	#14 (0.1820″)	PH 3
1/4″	1/4-20	#7 (0.2010″)	1/4-28	#3 (0.2130″)	PH 3
5/16″	5/16-18	F (0.2570″)	5/16-24	I (0.2720″)	PH 3
3/8″	3/8-16	5/16″ (0.3125″)	3/8-24	Q (0.3320″)	PH 4
1/2″	1/2-13	27/64″ (0.4219″)	1/2-20	29/64″ (0.4531″)	PH 4

Number, letter and fractional drills with their diameters in inches. In hard or tough materials, a slightly larger drill (less thread) makes tapping easier with little loss of strength.

Calculator

Round Head Screw Selector & Weight Estimator

Pick the size, thread, length and material. You get the head size, the driver, the tap drill and an estimate of the weight of your order.

Screw & order

Size

Thread

Length

Material

Quantity, pcs

Head and driver data from ASME B18.6.3. Weight is our estimate: a dome-shaped head plus a fully threaded body, calibrated against published screw weight tables, slot and recess not deducted. Densities: steel 7.85, 18-8 7.93, 316 8.0, brass 8.53 g/cm³.

Result

2.74

g per screw

2.74

kg for the order

Head dia. A:0.334–0.359″

Head dia., mm:8.5–9.1 mm

Head height H:0.123–0.137″

Driver:PH 2 or slot 0.050–0.060″

Tap drill:#25 (0.1495″, 75 %)

Overall length, max:0.887″

Materials

Round Head Screw Materials & Finishes

Material	Typical finish	Best for
18-8 stainless (304 / 305)	Plain, passivated	General purpose, indoor and outdoor
316 stainless	Plain, passivated	Marine, chemical and food equipment
Brass	Plain or nickel plated	Electrical terminals, decorative hardware
Low-carbon steel	Zinc plated, black oxide	Dry indoor assembly at low cost

18-8 stainless

304 · 305

The grade in the photo; 305 heads well cold.

304 305

316 stainless

Marine grade

For salt, chlorides and cleaning chemicals.

316 316L

Brass

Cold-heading brass

Conductive, non-magnetic, polishes well.

C26000 C27000

Low-carbon steel

Zinc plated

Economical machine and wood screws.

1018 1022

Manufacturing

How Our Round Head Screws Are Made

1

Wire

Stainless, brass or steel wire, certified by heat or lot.

2

Cold heading

Dome and Phillips recess formed together; slots punched or sawn.

3

Thread rolling

UNC / UNF or wood screw threads rolled.

4

Cleaning

Degreased; stainless passivated where specified.

5

Finishing

Zinc, black oxide or nickel plating.

6

Inspection

Head, recess and thread gauged; lot sealed.

Applications

Where Our Round Head Screws Are Used

Electrical

Switches, sockets, terminal blocks and panels.

Instruments

Meters, gauges and control housings.

Hardware

Hinges, latches, handles and nameplates.

Furniture & woodwork

DIN 96 and DIN 7996 wood screws, slotted for a traditional look.

Marine fittings

316 stainless and brass round heads on deck hardware.

Repair & restoration

Exact replacements for original slotted round heads.

Quality & testing

Round Head Screw Inspection & Certification

Check	Method	Applied to
Head diameter & height	Micrometer: A, H	Every lot
Slot	Width J and depth T gauged	Slotted lots
Phillips recess	Penetration gauge	Phillips lots
Thread	GO / NO-GO ring gauges	Every lot
Length	Measured under the head	Every lot
Material	PMI / chemical analysis	Stainless and brass lots

Every shipment includes

Mill certificate with heat number
Dimensional report
Lot number on every box

On request

EN 10204 3.1 certificate
Salt spray test for plated lots
Count-checked kits and labels

FAQ

Round Head Screw Questions, Answered

A round head screw has a high, domed head with a flat bearing face underneath. Inch round head machine screws are made to ASME B18.6.3 with a slotted or Phillips drive; metric round head wood screws are made to DIN 96 (slotted) and DIN 7996 (cross recessed). The dome gives a finished look and has no sharp edges.

A round head is a full dome; a pan head has straighter sides and a flatter top. At size No. 6, an ASME B18.6.3 round head is up to 0.260 in across and 0.103 in high, while a Phillips pan head is up to 0.270 in across and 0.097 in high. The pan head gives a slightly larger bearing face for the same size.

A truss head is wider and lower: at No. 10 it is up to 0.448 in across and 0.118 in high, against 0.359 in and 0.137 in for the round head, so it suits thin sheet and large holes. A binding head has straight sides and a slightly domed top; it is used on electrical terminals and binding posts.

For Phillips round heads to ASME B18.6.3: a No. 1 driver for sizes No. 2 to No. 4, No. 2 for No. 5 to No. 10, No. 3 for No. 12 to 5/16 in and No. 4 for 3/8 and 1/2 in. For slotted heads, choose a blade that fills the slot: the No. 10 slot is 0.050 to 0.060 in wide.

The thread decides it, not the head. For about 75 percent thread: No. 4-40 takes a No. 43 drill, No. 6-32 a No. 36, No. 8-32 a No. 29, No. 10-24 a No. 25, No. 10-32 a No. 21 and 1/4-20 a No. 7. Our table and calculator list every size from No. 2 to 1/2 in.

From the flat underside of the head to the end of the screw. The dome is not included, so a No. 10-24 × 3/4 in round head screw is 3/4 in under the head and up to 0.887 in overall.

Metric machine screws are normally specified with pan heads (ISO 1580 slotted, ISO 7045 cross recessed) or button heads (ISO 7380). Metric round heads remain standard for wood screws (DIN 96 and DIN 7996), and we make metric round head machine screws to customer drawings.

Most often 18-8 stainless steel (304 or 305), 316 stainless for marine and chemical service, brass for electrical and decorative use, and zinc-plated low-carbon steel for general assembly. The screw in our photo is 18-8 stainless with a Phillips recess.